Tabletop RPG idea of the day: a system for resolving attacks in combat. I don’t think I’ve ever seen anything exactly like it.

Background: One standard for making an attack is the attacker rolling dice to overcome a static defense value, such as “armor class.” Another is the attacker rolling dice to hit, and the defender rolling dice to prevent the hit. This ensures that players never have to sit by passively and await their doom when someone attacks them, but at the cost of added time and complexity. Numenera splits the difference by always having the player roll: an attack roll on the offense, and a defense roll when defending.

In the event of a successful hit, damage is almost always a variable roll. Numenera, and probably other systems, substitute a fixed value based on the weapon or weapon type. The White Wolf system is notable for having damage directly correspond to the number of successes rolled on the attack, in a dice-pool system.

One more piece: a number of games have used the idea of a die scale: an effect that is normally determined by a d6 might call for a d8 when enhanced, or a d4 when reduced.

The idea: During combat, both the attacker and defender make rolls. Each might have the ability to choose between several types, as well: the defender might have the option to roll a dodge, a parry, or to simply accept the attack against them and attempt a counter.

The attacker’s weapon has a base damage die (such as d6). More success on the attack roll slides the value upwards – to d8, d10, d12, and so on. This neatly includes a “critical hit”-type effect of increasing severity for increasingly expertly executed attacks. On the other hand, more success on the defense roll slides the value back down. My assumption is a system calibrated so that a perfect tie results in minimal effect: a single point of damage, but this can be adjusted depending on how bloody and dangerous you want combat to be. Obviously, greater success in defense eliminates damage entirely.

If you want to add special combat effects and options, this is where they would come in. The attacker can declare certain goals before making the roll, such as disarming their target, striking a specific body part, or even moving to short range while avoiding a longer-range weapon, such as a swordsman attempting to close in past the point of a spear. Each goal would have a specific cost in “steps” on the damage scale; if that cost slides the scale down to zero, then the move was too difficult to pull off.

Example: Bob the swordsman faces off against a troll wielding a club. Knowing that he probably can’t kill it in one blow, he hopes to strike its hand and force it to drop its weapon. Since a hand is a small and mobile target, his attack roll must beat its defense roll by three steps. Any less and he simply misses, causing no damage and no effect. Any more, and he manages to do a little extra damage to it as icing on the cake.

On the other hand, there may be effects that take place when defense is better than attack. Instead of steps below zero damage in to negative territory being “wasted,” they may count as a sort of critical fumble, allowing the defender to disarm, unbalance, or even harm the attacker. Unlike the cost in steps that the attacker faces, there would probably be a threshold beyond which an effect becomes available for the defender to choose.

Example: Bob has disarmed the troll, but now it’s angry and it still has long, sharp claws. It takes a swipe at him – but its roll is very poor and Bob does well. Perhaps it failed to hit at all by four steps (i.e. the damage roll went to four steps below zero). And perhaps there’s a two-step threshold for “unbalance,” forcing your opponent to go last in the next round, and a four-step threshold for “riposte,” allowing you to counterattack. Bob chooses riposte, and is able to make another attack for free.

Thoughts: This kind of combat would be a little harder to learn and get used to, and the optional customization threatens to become a sprawl of finicky situational rules and sub-sub-systems. It would require that everybody at the table have a full complement of die types, and combat would be a lot more variable (“swingy,” as they say) than the all-nothing-or-double standard familiar to players of D&D, in which you either hit, miss, or crit.

On the other hand, once you’ve gotten the hang of it this should be a relatively quick and simple system to use in play. It gives both defender and attacker an increased range of options without piling on the number of rolls to be made or subsystems to be consulted. The variability has a positive side as well, adding uncertainty and excitement to a fight – but in a way that is directly tied to the relative skill of the combatants instead of feeling arbitrary.

The bottom line, as always, is that practice overrides theory and whatever works (or doesn’t) for a specific group should inform that group’s play style. But overall I like this idea, and feel it would represent an incremental improvement on standard D&D-style combat.